This invention relates to a composite polymeric material with electrical conductivity determined by stress-tuning of the conductor-polymer composite. The material finds utility as a sensor for environmental factors that alter the strain state of the polymeric composite.
Martin et al. (U.S. Pat. No. 6,194,769), which is incorporated herein by reference, reports a class of sensor devices comprising field-structured conducting composites comprising a textured distribution of conducting magnetic particles. The conducting properties of such field-structured materials can be precisely controlled during fabrication so as to exhibit a large change in electrical conductivity when subject to any environmental influence which deforms or swells the composite. Influences which can be so detected include shear and tensile strains, temperature change, humidity, magnetic field, electromagnetic radiation, and the presence or absence of certain chemicals.
Martin et al. (U.S. Pat. No. 6,290,868), which is incorporated herein by reference, reports a class of composite materials, called field-structured composite (FSC) materials, which comprise an oriented aggregate structure made of magnetic particles suspended in a nonmagnetic medium, and to a new class of processes for their manufacture.
Martin et al. (U.S. Pat. No. 6,844,378), which is incorporated herein by reference, reports a method of producing three-dimensional particle structures with enhanced magnetic susceptibility in three dimensions by applying a triaxial energetic field to a magnetic particle suspension and subsequently stabilizing the particle structure. Combinations of direct current and alternating current fields in three dimensions produce particle gel structures, honeycomb structures, and foam-like structures.